1. Field of the Invention
The present invention relates to a device to control and check the quality of threaded parts, and more particularly to a high output device which automatically checks the threads in and on threaded parts.
2. Description of Related Art
In the production of high volume threaded parts, it is important to be sure that all parts are properly threaded. Many of these parts are used in assemblies where the fasteners are driven with automatic equipment. Even one unthreaded part in 10,000 can cause expensive downtime.
Up until now, nearly all thread confirming (or thread acceptance gauging) has been done by hand, on a sampling basis. For example, if 24,000 nuts are being produced an hour, then one out of every 1,000 might be checked, or 24 pieces in the one-hour period. This practice has proven inadequate, however. It is very easy for the tap (or other thread-forming device) to become broken, or worn, or not engage far enough; or for dirt or metal scrap to lodge in the threads. Sampling can't catch all these problems all of the time.
In U.S. Pat. No. 3,539,006, Hamna et al disclose a method and apparatus for inspecting annular articles such as nuts. A pair of unthreaded probes are used to check the diameter of the opening. Peplinski in U.S. Pat. No. 4,926,700 discloses an apparatus to test whether a threaded blind bore has been properly formed. Torque on a nut driver is measured. Also an electrical contact point on a driver portion indicates when the test plug has reached a desired depth in the test piece. In U.S. Pat. No. 5,823,356, Goodrich et al disclose an apparatus for inspecting threaded members. A constant speed rotary threaded fastener is engaged by a master thread gage for a predetermined amount of time to indicate acceptability of the fastener.